Abrasive grinders



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` ABRAsIvE GRINDERS Filed Jan. 2'?, 1956 IN V EN TOR.

United States Patent O ABRASIVE GRINDERS John F. Kopczynski, North Tonawanda, N. Y.

Application January 27, 1956, Serial No. 561,857

7 Claims. (Cl. 51-168) This invention relates to abrasive grinders, and more particularly to those having abrasive wheels of relatively small diameter on a small shaft.

An object of this invention is to provide an improved, simple, practical, durable and relatively inexpensive grinder which may be used for effectively grinding or finishing the interiors of recesses and passages, which will effectively withstand centrifugal forces at high speeds, and which has a superior bond between the grinding wheel and its mounting shank.

Another object is to provide an improved grinder on the end of a shaft, with which the abrasive wheel is securely confined on the shaft for positive rotation therewith and secured or anchored firmly against endwise movement along the shaft in both directions, and which has a mounting shank rigid enough to avoid whipping in use at high speeds, particularly when the shank is extended from the collet for deep hole grinding.

Another object is to provide an improved and simple method of making small diameter shafts for mounting small grinder wheels which will resist whipping and flexing in use.

Other objects and advantages will be apparent from the following description of two embodiments of the invention, and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

Fig. l is a side elevation of a small diameter, abrasive wheel confined on the free end of a small shaft for rotation therewith, in accordance with this invention;

Fig. 2 is an elevation of the same at the abrasive wheel end;

Fig. 3 is a perspective of the end part of the shaft which mounts the abrasive wheel before the wheel is applied thereto;

Fig. 4 is a schematic View illustrating how the flutes are ground;

Fig. 5 is a side elevation of the wheel which forms the flutes;

Fig. 6 is an end elevation of the shaft as the first fiutes are being formed therein; and

Fig. 7 is a longitudinal,` sectional elevation through an abrasive wheel and the shaft `end on which the wheel is mounted, and illustrating a modification of the invention.

In the embodiment of the invention illustrated in Figs. 1 to 3, the shaft 1, which mounts the abrasive wheel 2, has a body portion 3 of cylindrical shape which is connected to a reduced, free end portion 4 by an intermediate portion 5 that is generally tapered from the large end` portion 3 to the free, reduced end portion 4. Fingers 6 extend from the end of the body portion 3 that is adjacent the intermediate portion along and past the intermediate portion 5, and a short distance along and spaced from the reduced end portion 4. These fingers 6 are spaced apart around the periphery of the portion 3, with their outer faces being endwise continuations of the periphery of the body portion 3.

The reduced end portion 4 has adjacent to but slightly spaced from its free end an annular, peripheral groove or channel 7, the outer side wall of which constitutes a shoulder 8 on the periphery of the end portion 4 that faces toward the fingers 6. The abrasive Wheel 2 is cast or molded directly upon and concentrically of the reduced end portion 4, to extend from the free end face of the shaft at its reduced end to and along said fingers for at least part of the length of the fingers, as shown in Fig. l. Some of the abrasive wheel enters and fills the groove 7 and engages against the abutment 8, and the wheel 2 receives Within an end face the ends of the fingers 6. The fingers and the abutment 8 serve to prevent endwise movement of the abrasive wheel on the shaft and the lingers, because of their being embedded in the end face of the abrasive wheel, cause positive rotation of that wheel with the shaft.

In the embodiment of the invention shown in Fig. 7, the shaft 9 is similar to the shaft 1, except that instead of the groove 7, the reduced end 10 at its free end is provided with an external, peripheral flange or head 11 which provides an abutment 12 that corresponds in functionto the abutment 8 of Figs. l to 3, and faces the fingers 13 that correspond to the fingers 6 of Figs. l. to 3. The shaft 9 is similar to the shaft 1 except that the groove 7 of Figs. l to 3 is replaced by the external, peripheral flange or head 11. The abrasive wheel 14 is cast in one piece upon the reduced end 10 of the shaft 9 and preferably extends farther along the intermediate portion to include slightly the larger part of the shaft 9, as shown. in Fig. 7. The fingers 13 cause positive rotation of wheel 14 with the shaft, and the shoulder 12, near the side of the Wheel, and the fingers and intermediate portion near the other side of the wheel, prevent movement of the wheel 14l endwise on the shaft 9 in both directions.

The fingers 6 and 13 may be formed in the end of the larger part of the shaft by grinding or machining fiutes in the end of the large portion of the shaft adjacent the reduced end portion. For example, a grinding element 15, such as shown in Fig. 5, may be disposed as shown in Fig. 4, and moved along the shaft inthe direction of the arrow until it reaches the position shown in dash lines in Fig. 4. The shaft 16 which mounts the wheel or element 15 is disposed crosswise of and offset laterally from the shaft 1 or 9, and is rotatably operated to grind the flutes as the shaft 16 is moved in the direction of the arrow in Fig. 4. The wheel 15 has a grooved periphery which, in transverse section, is an arc of a circle having a radius equal to the radius of the reduced end of the shaft. After one flute is ground as shown in Figs. 4 and 6, the shaft is rotated about its longitudinal axis through part of a revolution, such as one-third of a. revolution, and then another flute is ground in the end of the larger part of the shaft. After this second flute is ground, the shaft is rotated through another third of a revolution and the third fiute ground in a similar manner. This provides the three fingers 6 or 13, because the flutes preferably intersect one another until they` rise partly in the inter,- mediate portion where the fingers merge into the intermediate portion. t

The manner in which the wheel is mounted on the shaft provides a secure, driving anchorage for the wheel, and the diameter of the abrasive Wheel can, if desired, be made quite small and only slightly larger than the larger end diameter of the shaft, which is often very advantageous in finishing the inside of small recesses or passages in an object being Worked on. The shaft with flutes could be made by forging or casting instead of by grinding, if desired.

Important features of this invention are the antiwhipping characteristic of the grinder, its ability to with..

stand centrifugal forces at high speeds of rotation and work pressure against the grinding wheel, and the firmness of the bond between the grinding wheel and the shank. In small diameter grinding wheels for grinding small diameter recesses or passages, the Wheel and its mounting shank are both necessarily small in diameter, so thatthe mounting shank is particularly subject to exing due to work pressure, to centrifugal forces at high speeds, and to a tendency to whip at the part of smallest diameter. A relatively small diameter mounting shank is also desirable in order to have maximum grinding wheel life,.yet this small diameter of the mounting shank increases its tendency to whip and tlex at high rotary speeds and under high Work pressures. The gradual blending radius between the smallest diameter part of the shank and the larger diameter part reduces the tendency of the shank to flex and Whip at high rotary speeds and high Work pressure. The spring fingers or prongs that extend from the larger diameter part of the shank and are embedded in the grinder Wheel also aid materially in reducing any tendency of the shank to liex and whip. The shoulder on the free end of the small diameter part of the' shank that engages with one end of the grinder wheel and the prongs or fingers that are embedded in the opposite end of the grinder wheel serve to eifectively hold the grinder wheel iirmly on the shank and resist whipping of the shank and also any tendency of the wheel to ex the mounting shank at high rotary speeds. This harnesses the non-flexibility of the grinding wheel to resist whipping of the smaller diameter part of the mounting shank. By this means the rigidity of the larger diameter part of the mounting shank is conveyed to the very tip or free end of the grinder wheel without reducing the maximum life of the Wheel.

It will be understood that various changes in the details and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principle and scope of the invention as eX- pressed in the appended claims.

I claim:

1. An improved grinder comprising a shaft having one end portion of smaller cross sectional area than the other end portion, and an intermediate portion connecting the two end portions and increasing in diameter from said one end portion to the other end portion, said other end portion at its junction with said intermediate portion having ngers extending endwise therefrom past ysaid intermediate portion and overrunning somewhat with said one end portion, the outer faces of said fingers being continuations of the peripheral surface of said other end, and an abrasive wheel secured on said one end portion and including within it the ends of said ngers, said one end portion having adjacent its free end a peripheral shoulder facing said fingers, and said wheel abutting said shoulder and said lingers to prevent endwise movement of said wheel along said shaft in both directions, and said fingers also causing rotation of said wheel with said shaft.

2. The grinder as set forth in claim l, and said wheel being molded on said shaft as an integral wheel.

3. The grinder as set forth in claim 1, and said wheel being molded on said shaft as an integral wheel, and said fingers at their free end portions being spaced from said one end portion.

4. A grinder comprising a shaft having a relatively large end portion and a relatively small end portion connected by an intermediate portion, said large end portion having peripherally spaced ngers extending from its end at its junction with the intermediate portion along said intermediate portion toward said small end portion, and said small end portion having in its periphery a shoulder facing said lingers, and an abrasive wheel molded on said small end portion to include between its end faces the end portions of said ngers and also said shoulder, whereby the shoulder and fingers resist movement of said wheel in both directions lengthwise on said shaft and said ngers engaged in said wheel cause positive rotation of said wheel with said shaft.

5. A grinder comprising a shaft having a relatively large end portion and a relatively small end portion connected by an intermediate portion, said large end portion having peripherally spaced fingers extending from its end at its junction with the intermediate portion along said intermediate portion toward said small end portion, and said small end portion having yin its periphery an annular groove, and an abrasive wheel cast on said one end portion including said groove and the free ends of said lingers, whereby said fingers will positively cause said wheel to rotate with said shaft and the part of said wheel moldedv in said groove will resist endwise movement of said wheel on said shaft in both directions.

6. A grinder comprising a shaft having a relatively large end portion and a relatively small end portion connected by an intermediate portion, said large end portion having peripherally spaced fingers extending from its end at its junction with the intermediate portion along said intermediate portion toward said small end portion, and said small end portion having in its periphery and adjacent its free end, an annular groove, and an abrasive wheel cast on said one end portion including said groove and the free ends of said fingers, whereby said fingers will positively cause said wheel to rotate with said shaft and the part of said wheel molded in said groove will resist endwise movement of said Wheel on said shaft in both directions.

7. The method of making a mounting shaft for a grinder wheel vwhich comprises machining a cylindrical shaft to form a cylindrical portion at one end and a reduced, shouldered portion at the Vother end, thenmachining slots into the inner end face of the larger end portion, with a rotary tool having a machining, peripheral surface that in transverse cross section is concave and an arc of a circle of approximately the same radius as the radius of the smaller end portion of the shaft, the slots being spaced apartperipherally of the large end portion of the shaft but close enough together to form three sided fingers projecting from the inner end of the large end portion which are spaced at their free ends from the small end and intermediate portions, one side of which is the uncut, cylindrical' outer face of the large end portion, and the other two sides of which are plane faces that intersect-in a dihedral angle.

References Cited in the le of this patent UNITED STATES PATENTS 339,544 Graham Apr. 6, 1886 

